Preparation, characterization and photocatalytic activity of N-doped TiO₂ nanocrystals

N-doped TiO₂ nanocrystals were prepared using titanium alkoxide as precipitant with different proportional materials. The products were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and UV-vis diffuse reflectance spectra. It is confirmed experimentally that the photocatalytic activity of N-doped TiO₂ is much higher than that of Degussa P25, when used for the degradation of crystal violet. The degradation kinetics follows an apparent first-order reaction, which is consistent with a generally observed Langmuir-Hinshelwood mechanism. The doping of TiO₂ with nitrogen significantly increases the absorption in the region of visible light. The energy of the band gap of N-doped TiO₂ is 2.92 eV. The better performance of N-doped TiO₂ can be explained by the fact that it is also excited with longer-wavelength light.